Mr Abure was arrested on Wednesday after attending a meeting with the State Security Service in Benin City.
The Labour Party (LP) presidential candidate, Peter Obi, said it is "demeaning and intolerable" watching the "distressing image" of the LP National Chairperson, Julius Abure, lying on the ground during his arrest by the police.
Mr Abure was arrested on Wednesday in Benin City, Edo State, by police operatives from Zone 5 Benin for alleged attempted murder, illegal possession of firearms, and other offences.
Viral videos of the arrest showed Mr Abure being manhandled by police officers as party supporters fought to resist his arrest, Channels TV reported.
Reacting to the arrest on his X handle, Mr Obi said the actions of the police officers "epitomise the pinnacle of rascality and serve to egregiously tarnish the already regrettable perception of our nation as one plagued by lawlessness."
He said, "Such behaviour must not only be denounced but also actively addressed to uphold the principles of justice and respect for the dignity of the individual within our society.
"It is crucial to emphasise that as a leader within the Labour Party, Mr Abure represents, both personally and statutorily, as the incumbent Chairman of the LP, the face of political opposition in Nigeria. Most importantly, political parties are institutions of democratic statehood and ought to that extent be accorded due respect."
Continuing, Mr Obi warned that no pretext should be employed to stifle opposition in the country and demanded that Mr Abure be granted bail based on his status while the investigation of the alleged offences could go on.
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LP reacts
The LP held ward congresses on Tuesday to elect delegates ahead of its governorship primary scheduled for Friday.
Giving details of the arrest, the national spokesperson of LP, Obiora Ifoh, said Mr Abure accompanied by governorship aspirants honoured a scheduled security meeting with the State Security Service (SSS) in Benin on Wednesday morning.
"Mr Abure was, however, arrested after the meeting by a combined team of SSS and police officers."
Mr Ifoh, who disclosed this in a statement on Wednesday, said the Edo State chairperson of the party, Kelly Ogbaloi, was also arrested.
Mr Ifoh said the police turned down efforts by party leaders to have access to the Zone 5 headquarters due to a crowd of party supporters who were expressing displeasure over Mr Abure's arrest.
"A police source informed the party officials and other governorship aspirants at the gate of the police headquarters that the arrest was in connection to a protest letter by one of the expelled members of the party loyal to the Apapa dissident camp.
"The source also confirmed that the arrest was not unconnected to the ongoing party primary and the possible candidate that will emerge which the state government is vehemently opposed to."
"He informed that the arrest was to frustrate the primary process and possibly interrupt the party's participation in the governorship election," Mr Ifoh alleged.
